The present invention relates to a semiconductor device in which a semiconductor element is mounted in a substrate and a method of manufacturing the semiconductor device.
A structure of mounting a semiconductor element has been variously proposed. For example, a structure in which a predefined semiconductor element is mounted in a concave part (or cavity) formed in a substrate has been proposed.
For example, if an MEMS (Micro Electro Mechanical System) element serving as a kind of semiconductor element is mounted, it is advantageous that package miniaturization or microfabrication is possible and also the element is easily sealed when the element is mounted in the concave part.
Further, a substrate for mounting a semiconductor element is developing from a conventional ceramic substrate to a semiconductor (for example, silicon) substrate in which miniaturization or microfabrication is facilitated.
[Patent Document 1]
Unexamined Japanese Patent Application Publication No. 2000-39371
However, a silicon wafer capable of being conventionally easily obtained as a current semiconductor substrate has the thickness of about 600 μm to 800 μm, and has a problem in that it is difficult to increase the depth of a concave part for mounting a semiconductor element. For example, if a special substrate thicker than the semiconductor substrate capable of being conventionally obtained is made, the concave part can be deeply formed, but the cost of manufacturing the semiconductor substrate increases. This is not realistic when the productivity upon production is considered.
Further, if the concave part is deeply formed, there is a problem in that the variation in a form (particularly, flatness) of the concave part is increased and the yield (or productivity) of a semiconductor device to be formed is degraded.
Further, a method disclosed in Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2000-39371) forms a cavity by laminating semiconductor substrates, but the cavity is used to form a pressure detection element (or diaphragm). A method and structure for mounting a semiconductor element in the cavity are not disclosed in detail.